1996 Johnson/Evinrude Outboards 25, 35 3-Cylinder Service Manual, Page 128Get this manual
Engine Temperature Check The Markal Thermomelt Stik is heat-sensitive marker that melts on contact with surface of specific temperatureOne source of Thermomelt Stiks is Stevens Instrument Company[}] At least two Thermomelt Stiks or digital pyrometer should be used to accurately determine the engine's operating temperaturesThe Thermomelt Stik mark will appear dull and chalky when the surface marked is below the Stik's rated temperature When the surface exceeds the Stik's rated temperature, the mark will appear liquid and glossy
To achieve accurate and consistent readings, engine temperature must be gauged at the top of the thermostat pocket
INote For the following engine operating temperatures and RPM
figures to be correct, the inlet water temperature must be 70 10 (21 C)Pyrometer Procedure
1 Twist and remove spark plug leads before changing propellers to avoid accidental starting of engine1Install correct test propeller and place engine in test tank2Start engine and run at 3000 RPM for at least five minutes